Genetic Evaluation On Different Mating Combinations Of Liriodendron Based On Progeny Test Trials At Young Stage

In this paper,the genetic evaluation of different mating combinations was done based on progeny test trails both at nursery and at young stage plantation.At nursery stage,49 different mating combinations of Liriodendron were tested at 3 sites,the growth,rooting ability,and photosynthetic characteristics for each combination were measured.At young plantation stage,68 different mating combinations of Liriodendron were tested at 2 different locations.The main results were as follows:There were significant variations of growth at young stage existed among different combinations,different sits,and among individuals within combination.. Compared with open-pollinated combinations,control pollination combinations showed great heterosis.The estimated family heritabilities of growth were more than 0.5,therefore it could be concluded that the growth of Liriodendron were intensively genetic controlled.Considering that family heritability was higher than individual heritability,early growth selection for Liriodendron should be focused on family selection.There were also significant variations of rooting abilities existed among different combinations in Liriodendron,rooting traits were stronger genetic controlled.A significant positive correlation was found between growth and rooting abilities.Similar to most species,the light saturation point was around 1200μmol.m^-2.s^-1 in Liriodendron.It seemed that Liriodendron had photosynthetic "lunch break" from August to September,and a similar monthly variation of net photosynthetic rate was found for each combination.The net photosynthetic rate correlated positively to chlorophyll content,growth,while correlated negatively to leaf area in Liriodendron.Based on those results above,10 excellent mating combinations and 25 superior trees in nursery stage and 10 excellent mating combinations and 30 superior trees in young plantation were primarily selected for further testing.There were significant interaction between genotype and environment in different mating combinations of Liriodendron.Of these tested combinations,4 combinations showed strong genetic stability.